Abstract:

Objectives: To optimize the conditions for ionic liquid-assisted extraction of flavonoids compounds from Herba
Lobelia chinensis using single factor and orthogonal array designs and consequently to establish a high performance liquid
chromatography (HPLC) method for simultaneous determination of rutin, quercetin, naringgenin, hesperetin, kaempferol and
apigenin in Herba Lobelia chinensis. Methods: The 6 compounds were separated on an InertSustain C18 (150 mm × 4.6 mm, 5 μm)
using a mobile phase consisting of methanol and acetic acid (pH 3.0) with gradient elution at a flow rate of 1.0 mL/min.
The detection wavelength was set at 285 nm. The column temperature was maintained at 35 ℃. Results: The optimum
extraction conditions for total flavonoids were determined as follows: 80% (V/V) aqueous methanol as extraction solvent;
solid-to-liquid ratio, 1:80 (g/mL); extraction time, 30 min; and ionic liquid concentration, 0.6 mol//L. Under these conditions,
rutin, quercetin, naringgenin, hesperetin, kaempferol and apigenin were separated satisfactorily. The limits of detection (LODs)
for these flavonoid compounds were 0.001 2, 0.002 3, 0.002 6, 0.000 2, 0.001 0 and 0.000 6 μg/mL, respectively. The recoveries
of spiked samples ranged from 91.77% to 102.53%. Conclusion: The proposed method is simple and rapid, and it can provide an
efficient means for the extraction, separation and determination of flavonoid compounds in Herba Lobelia chinensis.

Key words: high performance liquid chromatography, Herba Lobelia chinensis Lour., flavonoid compounds, ionic liquid, ultrasonic extraction